• New & Renewable Energy
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• v.10 no.1
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• pp.6-19
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• 2014

Organic Rankine cycle (ORC) has been widely used to convert renewable energy such as solar energy, geothermal energy, or waste energy etc., to electric power. For a small scale output power less than 10 kW, turbo-expander is not widely used than positive displacement expander. However, the turbo-expander has merits that it can operate well at off-design points. Usually, the available thermal energy for a small scale ORC is not supplied continuously. So, the mass flowrate should be adjusted in the expander to maintain the cycle. In this study, nozzles was adopted as stator to control the mass flowrate, and radial-type turbine was used as expander. The turbine operated at partial admission. R245fa was adopted as working fluid, and supersonic nozzle was designed to get the supersonic flow at the nozzle exit. When the inlet operating condition of the working fluid was varied corresponding to the fluctuation of the available thermal energy, optimal operating condition was investigated at off-design due to the variation of mass flowrate.

• New & Renewable Energy
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• v.19 no.2
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• pp.23-30
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• 2023

Vortex-induced vibrations are a type of flow-induced vibrations caused by alternating lift forces. With increasing demand for renewable energy, the application of vortex-induced vibrations to renewable energy has been widely studied. Vortex-induced vibrations for aquatic clean energy (VIVACE) converter is a renewable energy device that generates electricity from rivers or oceans using vortex-induced vibrations. To increase the design life and power harnessing capacity of the VIVACE converter, the estimation of fluid forces due to vortex-induced vibrations is essential. Herein, vortex-induced vibrations were experimentally tested, and their amplitude and frequency response were measured. The amplitude results showed four different branches: initial branch, upper branch, lower branch, and desynchronization range. According to the fluid force coefficient results, the maximum lift coefficient occurred at the upper branch. Additionally, a mathematical model is proposed to estimate fluid forces due to vortex-induced vibrations without using measurement devices. This mathematical model enables the estimation of fluid force coefficients and phase lag using amplitude and frequency response of vortex-induced vibrations.

• Journal of The Korean Society of Agricultural Engineers
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• v.64 no.4
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• pp.21-30
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• 2022

Renewable energy systems aim to achieve carbon neutrality and replace fossil fuels. Photovoltaic technologies are the most widely used renewable energy. However, they require a large operating area, thereby decreasing available farmland. Accordingly, agrivoltaic systems (AVSs)-innovative smart farm technologies that utilize solar energy for crop growth and electricity production-are attracting attention. Although several empirical studies on these systems have been conducted, comprehensive research on their design is lacking, and no standard model suitable for South Korea has been developed. Therefore, this study created an integral design of AVS reflecting domestic crop cultivation conditions and conducted a structural analysis for safety assessment. The shading ratio, planting distance, and agricultural machinery work of the system were determined. In addition, national construction standards were applied to evaluate their structural safety using a finite element analysis. Through this, the safety of this system was ensured, and structural considerations were put forward. It is expected that the AVS model will allow for a stable utilization of renewable energy and smart farm technologies in rural areas.

• The KIPS Transactions:PartA
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• v.10A no.6
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• pp.757-768
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• 2003

Recently, the renewable energy resources play an important role as an energy resources of future due to an environmental pollution and lack of resources and so on. The development and diffusion of information systems related to renewable energy resources have been driven actively abroad. However, at domestic an efficient history management for renewable energy resource data and web retrieve service are not provided. Therefore, in this paper, we propose a history data management system for the renewable energy resources, which stores and manages vast history information of renewable energy resource data systematically. This system collects renewable energy resource data in the outside observation system and stores them in the history database. The stored Information is retrieved through the history query process and can be provided in various forms - table, graph, chart and counter line, etc. - on the internet. Especially, the proposed system manages the history data in real-time so the latest information is always provided to the users through the web interface.

• Journal of the Korean Solar Energy Society
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• v.26 no.3
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• pp.79-87
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• 2006

This study aims to presents the applicability of apartment building for renewable energy systems using method of uncomplicated calculation and computer simulation. According to the weather conditions (NASA Surface meteorology and Solar Energy) analysis, it has been found that photovoltaic and wind power system can be applied to apartment buildings application. In case study considering layout and block plan, adaptation of solar water heating, photovoltaic and wind energy system to apartment buildings was proved to produce a profit. And the application strategies of renewable energy systems can be used not only for the investment decisions for economic analysis but also for the comparative analysis of uncomplicated calculation and computer simulation.

• 한국태양에너지학회:학술대회논문집
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• 2008.11a
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• pp.337-340
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• 2008

As a 'Construction of Information System on GIS based and Resource Map', establish the strategic of design about construction of Spatial Data Warehouse for New & Renewable Energy For Construction of comfortable Spatial Data Warehouse, It suggested The Construction of Spatial Data Warehouse on Block(Grid) Based with Analyze into the old Data & Method of Study. For Decide the Block(Grid) Size, We need The Study of Data & Method. Also, we expect Standardize The Process of Change & Apply with Data. make the best use of New & Renewable Energy Part

• Journal of the Korean Solar Energy Society
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• v.28 no.1
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• pp.57-64
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• 2008

According to the Fourth Assessment Report of Intergovernmental Panel on Climate Change(IPCC) Working Group III, climate change is already in progress around the world, and it is necessary to execute mitigation in order to minimize adverse impacts. This paper suggests future climate change needs, employing IPCC Special Report on Emissions Scenarios(SRES) to predict temperature rises over the next 100 years. This information can be used to develop sustainable architecture applications for energy efficient buildings and renewable energy. Such climate changes could also affected the resent supplies of renewable energy sources. This paper discusses one recent Fourth Assessment Report of IPPC (Mitigation of Climate Change) and the Hadley Centre climate simulation of relevant data series for South Korea.

• Journal of Power Electronics
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• v.19 no.6
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• pp.1486-1495
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• 2019

Dealing with the DC link fault poses a technical problem for an HVDC based on a modular multilevel converter. The fault suppressing mechanisms of several sub-module topologies with DC fault current blocking capacity are examined in this paper. An improved half-bridge sub-module topology with double direction control switch is also designed to address the additional power consumption problem, and a sub-module topology called hybrid double direction blocking sub module (HDDBSM) is proposed. The DC fault suppression characteristics and sub-module capacitor voltage balance problem is also analyzed, and a self-startup method is designed according to the number of capacitors. The simulation model in PSCAD/EMTDC is built to verify the self-startup process and the DC link fault suppression features.

• Journal of the Korean Solar Energy Society
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• v.33 no.2
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• pp.64-69
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• 2013

According to the Fourth Assessment Report of Intergovernmental Panel on Climate Change(IPCC) Working Group III, climate change is already in progress around the world, and it is necessary to execute mitigation in order to minimize adverse impacts. This paper suggests future climate change needs, employing IPCC Special Report on Emissions Scenarios(SRES) to predict temperature rises over the next 100 years. This information can be used to develop sustainable architecture applications for energy efficient buildings and renewable energy. Such climate changes could also affected the present supplies of renewable energy sources. This paper discusses one recent Fourth Assessment Report of IPCC (Mitigation of Climate Change) and the Hadley Centre climate simulation of relevant data series for South Korea. Result of this research may improve consistency and reliability of simulation weather data or climate change in order to take advantage of SRES and PRECIS QUMP. It is expected that these calculated test reference years will be useful to the designers of solar energy systems, as well as those who need daily solar radiation data for South Korea. Also, those results may contribute zero carbon and design of sustainable architecture establishing future typical weather data that should be gone ahead to energy efficient building design using renewable energy systems.

• The Journal of Information Systems
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• v.28 no.1
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• pp.115-132
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• 2019

Purpose The purpose of this study is to explain the agrophotovolatic system built by the Korea South-East Power Company and to propose methods to activate the agrophotovolatic system for the development of the renewable energy industry. Design/methodology/approach We conducted a three-step simulation in order to design a photovoltaic module, and we built the agrophotovolatic system based on the results of the simulation. Then, we analyzed the monthly generation of power and the rice harvests produced on farmland using the photovoltaic module. Based on the results of the analysis, we proposed institutional improvements to increase the use of the agrophotovolatic system, and we proposed new business models to increase the participation of farmers and business persons. Findings When we compared the agrophotovolastic system with the general photovoltaic system, we found that the agrophotovoltaic system had higher utilization rates and power generation. An analysis of rice produced on farmland using the photovoltaic module showed that more than 80% of the rice produced on general farmland was harvested. We suggested activation plans that involved the revision of the farmland law and the introduction of renewable energy certificate (REC). We also proposed a land lease model and a farmer participation model as two new business models, and we conducted economic evaluations and sensitivity analyses for both models.